pulmonary clear cell adenocarcinoma

Extremely rare as a pure subtype—but over a third of mixed adenocarcinomas show at least some focal clear cell change. Tumor cells form sheets with at least focal tubal formation (the latter required for diagnosis) and may form papillae. Intracytoplasmic material is PAS-positive, diastase-sensitive—indicative of glycogen. Pure tumors have not been well-studied by IHC—one reported tumor was CK7+/CK20-/TTF-1+.